TY - JOUR T1 - (-)-N-3-Benzylphenobarbital is superior to omeprazole and (+)-N-3-benzylnirvanol as a CYP2C19 inhibitor in suspended human hepatocytes JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.120.000089 SP - DMD-AR-2020-000089 AU - Marie-Lynn Cuypers AU - Hugues Chanteux AU - Eric Gillent AU - Pierre Bonnaillie AU - Kenneth Saunders AU - Claire Beckers AU - Claude Delatour AU - Sylvie Dell'Aiera AU - Anna-Lena Ungell AU - Johan Nicolaï Y1 - 2020/01/01 UR - http://dmd.aspetjournals.org/content/early/2020/08/24/dmd.120.000089.abstract N2 - Early assessment of metabolism pathways of new chemical entities (NCEs) guides the understanding of drug-drug interactions (DDIs). Selective enzyme inhibitors are indispensable in cytochrome P450 (CYP) reaction phenotyping. The most commonly applied CYP2C19 inhibitor, omeprazole, lacks selectivity. Two promising alternatives, (+)-N-3-benzylnirvanol and (-)-N-3-benzylphenobarbital, are already used as CYP2C19 inhibitors in some in vitro studies with suspended human hepatocytes. However, a full validation proving their suitability in terms of CYP and non-CYP selectivity has not been presented in literature. The present study provides a thorough comparison between omeprazole, (+)-N-3-benzylnirvanol, and (-)-N-3-benzylphenobarbital in terms of potency and selectivity, and shows the superiority of (-)-N-3-benzylphenobarbital as a CYP2C19 inhibitor in suspended human hepatocytes. Furthermore, we evaluated the application of (-)-N-3-benzylphenobarbital to predict the in vivo contribution of CYP2C19 to drug metabolism (fmCYP2C19). A set of ten clinically used CYP2C19 substrates with reported in vivo fmCYP2C19 data was evaluated. FmCYP2C19, which was predicted using datafrom suspended human hepatocyte incubations, underestimated the in vivo fmCYP2C19. The use of a different hepatocyte batch with a different CYP3A4/CYP2C19 activity ratio, showed the impact of intrinsic CYP activities on the determination of fmCYP2C19. Overall, this study confirms the selective CYP2C19 inhibition by (-)-N-3-benzylphenobarbital over other CYP isoforms (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2D6, and CYP3A4) and clinically relevant non-CYP enzymes (AO, FMO3, NAT2, UGT1A1, UGT1A4, UGT2B7, UGT2B15) in suspended human hepatocytes. (-)-N-3-benzylphenobarbital is therefore the preferred CYP2C19 inhibitor to assess fmCYP2C19 in suspended human hepatocytes in comparison to omeprazole and (+)-N-3-benzylnirvanol. Significance Statement (-)-N-3-benzylphenobarbital is a more potent and selective inhibitor of CYP2C19 in suspended human hepatocytes than omeprazole. (-)-N-3-benzylphenobarbital can be used to predict the fraction metabolized by CYP2C19 in suspended human hepatocytes. ER -